tall order vs task

tall order and task both are nouns.

Word	Noun	Adjective	Verb	Adverb
tall order	Yes	No	No	No
task	Yes	No	Yes	No

As nouns, task is a hypernym of tall order; that is, task is a word with a broader meaning than tall order:

Other hypernyms of tall order include labor, labour, project, undertaking.

tall order (noun)	task (noun)
a formidable task or requirement	a specific piece of work required to be done as a duty or for a specific fee
	any piece of work that is undertaken or attempted

tall order (verb)	task (verb)
	use to the limit
	assign a task to